Life Sciences Commons^™

Biochemistry Of Trehalose Accumulation In The Spring Field Cricket, Gryllus Veletis, Alyssa R. Stephens

Electronic Thesis and Dissertation Repository

The freeze tolerant spring field cricket, Gryllus veletis, accumulates trehalose in the blood and tissues during cold acclimation. Trehalose is the main blood sugar in insects, thus its blood concentration is tightly regulated, and trehalose is readily metabolized. How do crickets modify their metabolism to accumulate trehalose in their hemolymph and tissues? I hypothesized that trehalose production, transport, and consumption were modified during the cold acclimation to facilitate trehalose accumulation. Trehalose and the trehalose-specific transporter, TRET-1, are distributed among all tissues, and trehalose accumulates in the hemolymph, fat body, Malpighian tubules, and gut. Trehalose production increases during cold acclimation …

Mechanisms Of Chloroperoxidases-Catalyzed Enantioselective Transformations From Spectroscopic And X-Ray Crystallographic Studies Of Enzyme-Substrate Complexes, Xiaoqing Tang

FIU Electronic Theses and Dissertations

The chloroperoxidase secreted from Caldariomyces fumago catalyzes broad spectrum of reactions. The crystallography combined with X-ray diffraction analysis was conducted to reveal recombinant CPO expressed in a modified Aspergillus niger system. Our results indicated that despite functional similarities with wild type CPO, recombinant CPO is over glycosylated with more mannose. Besides, ten iodide ion binding sites were identified in rCPO and six of them were found to be well superimposed on previously reported structure of the wild type CPO. Therefore, recombinant CPO shares almost the same structure with wild type CPO, and the Aspergillus niger is a potential system for …

Dual Control Of One Component Signaling: Mechanistic And Structural Insights Into El222 Active States, Uthama Phani R. Edupuganti

Dissertations, Theses, and Capstone Projects

Photoreceptors play a crucial role in signal transduction as specialized proteins which sense light as environmental stimuli and transduce the signal to control of downstream functions. Here we focus our attention on one class of these proteins, the Light-Oxygen-Voltage (LOV) domain, which is sensitive to blue light via an internally-bound flavin chromophore. Since their initial discovery in plant phototropins, many details of their photochemistry, chromophore interactions, and use with a diverse set of functional effectors have been described. However, several key details, especially a comprehensive understanding of signaling mechanism and its regulation, still remain elusive due in part to the …

Protonic Capacitor: Elucidating The Biological Significance Of Mitochondrial Cristae Formation, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

For decades, it was not entirely clear why mitochondria develop cristae? The work employing the transmembrane-electrostatic proton localization theory reported here has now provided a clear answer to this fundamental question. Surprisingly, the transmembrane-electrostatically localized proton concentration at a curved mitochondrial crista tip can be significantly higher than that at the relatively flat membrane plane regions where the proton-pumping respiratory supercomplexes are situated. The biological significance for mitochondrial cristae has now, for the first time, been elucidated at a protonic bioenergetics level: 1) The formation of cristae creates more mitochondrial inner membrane surface area and thus more protonic capacitance for …

Catalytic Mechanism For The Conversion Of Salicylate Into Catechol By The Flavin-Dependent Monooxygenase Salicylate Hydroxylase, Débora M. A. Costa, Stefanya V. Gómez, Simara S. De Araújo, Mozart S. Pereira, Rosemeire B. Alves, Denize C. Favaro, Alvan C. Hengge, Ronaldo A. P. Nagem, Tiago A. S. Brandão

Chemistry and Biochemistry Faculty Publications

Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7. We explored the mechanism of action of this enzyme in detail using a combination of structural and biophysical methods. NahG shares many structural and mechanistic features with other versatile flavin-dependent monooxygenases, with potential biocatalytic applications. The crystal structure at 2.0 Å resolution for the apo form of NahG adds a new snapshot preceding the FAD binding in flavin-dependent monooxygenases. The k_cat/K_m for the salicylate reaction catalyzed by the holo form is …

Mechanism Of Substrate Reduction By Nitrogenase, Nimesh Khadka

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogen (N) is a vital element of life and the main component of chemical fertilizer. The industrial Haber-Bosch process fulfills the demands of today’s nitrogen need and is therefore considered as one of the major scientific breakthroughs of the last century. However, the Haber-Bosch process operates at very high temperature and pressure, and requires fossils fuels to drive the reaction, making it an energy expensive process. The energy demand for this process accounts for almost 3% of the total global energy consumption. In addition, the rapid population growth, economic development and depletion of limited non-renewable fossil fuels have already created …

Intensity-Based Skeletonization Of Cryoem Gray-Scale Images Using A True Segmentation-Free Algorithm, Kamal Al Nasr, Chunmei Liu, Mugizi Rwebangira, Legand Burge, Jing He

Computer Science Faculty Publications

Cryo-electron microscopy is an experimental technique that is able to produce 3D gray-scale images of protein molecules. In contrast to other experimental techniques, cryo-electron microscopy is capable of visualizing large molecular complexes such as viruses and ribosomes. At medium resolution, the positions of the atoms are not visible and the process cannot proceed. The medium-resolution images produced by cryo-electron microscopy are used to derive the atomic structure of the proteins in de novo modeling. The skeletons of the 3D gray-scale images are used to interpret important information that is helpful in de novo modeling. Unfortunately, not all features of the …

The Magnitude And Mechanism Of Charge Enhancement Of Ch∙∙O H-Bonds, U. Adhikari, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Quantum calculations find that neutral methylamines and thioethers form complexes, with N-methylacetamide (NMA) as proton acceptor, with binding energies of 2–5 kcal/mol. This interaction is magnified by a factor of 4–9, bringing the binding energy up to as much as 20 kcal/mol, when a CH3+ group is added to the proton donor. Complexes prefer trifurcated arrangements, wherein three separate methyl groups donate a proton to the O acceptor. Binding energies lessen when the systems are immersed in solvents of increasing polarity, but the ionic complexes retain their favored status even in water. The binding energy is reduced when the methyl …

Structural And Mechanistic Investigations Of Phosphothreonine Lyase Class Of Enzymes, Alok Gopalkrishna Shenoy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Phosphorylation and dephosphorylation are a highly pervasive mechanism in biology that is used by the cell to modulate enzymes and proteins. The presence of a phosphate group can activate or deactivate an enzyme. The phosphate group is linked to a protein by a phosphoester bond that is known to be highly stable in cytoplasmic pH range. Thus the breaking and formation of these bonds need to be effected by enzymes.

Recent discovery of the activity carried out by certain virulence related proteins (OspF released by Shigella and SpvC released by Salmonella) have resulted in a necessity to create a new …

Characterization Of The Desorption Electrospray Ionization Mechanism Using Microscopic Imaging Of The Sample Surface, Michael Craig Wood

Theses and Dissertations

Desorption electrospray ionization (DESI) is an ambient ionization technique for mass spectrometry. This solvent based desorption ion source has wide applicability in surface analysis with minimal sample preparation. Interest in improving detection limits, broadening applications, and increasing the spatial resolution for chemical imaging has led to studies of the DESI mechanism. An inverted microscope has been used to image interactions between the DESI spray and test analytes on a glass surface. Microscopic images recorded with millisecond time resolution have provided important insights into the processes governing analyte transport and desorption. These insights are the basis of a rivulet-based model for …

Characterization Of The Substrate Specificity And Mechanism Of Protein Arginine Methyltransferase 1, Whitney Lyn Wooderchak

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Protein arginine methyltransferases (PRMTs) posttranslationally modify protein arginine residues. Type I PRMTs catalyze the formation of monomethylarginine (MMA) and asymmetric dimethylarginine (ADMA) via methyl group transfer from S-adenosyl methionine onto protein arginine residues. Type II PRMTs generate MMA and symmetric dimethylarginine. PRMT-methylation affects many biological processes. Although PRMTs are vital to normal development and function, PRMT-methylation is also linked to cardiovascular disease, stroke, multiple sclerosis, and cancer.

Thus far, nine human PRMT isoforms have been identified with orthologues present in yeast, plants, and fish. PRMT1 predominates, performing an estimated 85% of all protein arginine methylation in vivo. Yet, the substrate …

Ferritin: Mechanistic Studies And Electron Transfer Properties, Bo Zhang

Theses and Dissertations

Ferritins are ubiquitous iron storage proteins in living systems. Although much is known about the iron deposition process in ferritin and a mechanism has been developed, several important issues still remain unknown. One lingering question is the less than stoichiometric quantities of hydrogen peroxide detected in previous studies on animal ferritins. Extensive experimental data on identifying the species in competition for peroxide equivalents point to a surprising conclusion that H2O2 generated in the ferroxidase reaction is consumed by amine buffers that are commonly employed in in vitro ferritin studies, while non-nitrogen containing buffers, such as acetate, phosphate, and carbonate, do …